Test cases intended to document behavior and try to exhaustively explore the combinations.

Confidence

These tests are not yet considered 100% normative, in that some aspects of the current behavior are not desirable. This is expressed in the “confidence” field in the following table. Values:

Confidence	Interpretation
100%	this will remain recommended behavior
75%	unclear whether we will continue to accept this
50%	this will likely be deprecated but remain valid
25%	this could change in the future
0%	this is definitely bogus and will likely change in the future in some way

Tests

Test file	Self type	Pattern	Current elision behavior	Confidence
self.rs	Struct	Self	ignore self parameter	100%
struct.rs	Struct	Struct	ignore self parameter	100%
alias.rs	Struct	Alias	ignore self parameter	100%
ref-self.rs	Struct	&Self	take lifetime from &Self	100%
ref-mut-self.rs	Struct	&mut Self	take lifetime from &mut Self	100%
ref-struct.rs	Struct	&Struct	take lifetime from &Self	50%
ref-mut-struct.rs	Struct	&mut Struct	take lifetime from &mut Self	50%
ref-alias.rs	Struct	&Alias	ignore Alias	0%
ref-mut-alias.rs	Struct	&mut Alias	ignore Alias	0%
lt-self.rs	Struct<'a>	Self	ignore Self (and hence 'a)	25%
lt-struct.rs	Struct<'a>	Self	ignore Self (and hence 'a)	0%
lt-alias.rs	Alias<'a>	Self	ignore Self (and hence 'a)	0%
lt-ref-self.rs	Struct<'a>	&Self	take lifetime from &Self	75%

In each case, we test the following patterns:

• self: XXX
• self: Box<XXX>
• self: Pin<XXX>
• self: Box<Box<XXX>>
• self: Box<Pin<XXX>>

In the non-reference cases, Pin causes errors so we substitute Rc.

async fn

For each of the tests above we also check that async fn behaves as an fn would. These tests are in files named *-async.rs.

Legends:

• ✓ ⟹ Yes / Pass
• X ⟹ No
• α ⟹ lifetime mismatch
• β ⟹ cannot infer an appropriate lifetime
• γ ⟹ missing lifetime specifier

async file	Pass?	Conforms to fn?	How does it diverge? fn ⟶ async fn
self-async.rs	✓	✓	N/A
struct-async.rs	✓	✓	N/A
alias-async.rs	✓	✓	N/A
assoc-async.rs	✓	✓	N/A
ref-self-async.rs	X	✓	N/A
ref-mut-self-async.rs	X	✓	N/A
ref-struct-async.rs	X	✓	N/A
ref-mut-struct-async.rs	X	✓	N/A
ref-alias-async.rs	✓	✓	N/A
ref-assoc-async.rs	✓	✓	N/A
ref-mut-alias-async.rs	✓	✓	N/A
lt-self-async.rs	✓	✓	N/A
lt-struct-async.rs	✓	✓	N/A
lt-alias-async.rs	✓	✓	N/A
lt-assoc-async.rs	✓	✓	N/A
lt-ref-self-async.rs	X	✓	N/A